The present invention relates to a sheet humidifying device that humidities sheets, and to an image forming system equipped with the sheet humidifying device.
In an image forming apparatus of an electrophotographic type, namely, in a copying machine, a printer, a facsimile machine and a multifunction peripheral having functions of the aforesaid items, there is a problem that a sheet is curled and is deformed to be waved because a sheet is dehydrated in the course of heating in the heating and fixing process. As a device to solve this problem, there has been suggested a technology to humidify a sheet after the sheet has been processed in terms of fixing.
Unexamined Japanese Patent Application Publication No. 2007-58026 discloses a sheet humidifying device having therein a pair of porous rollers which convey a sheet and form a nip portion and water-supply rollers which are in contact with the humidifying rollers to supply water.
Water to be supplied to a sheet is supplied to the porous rollers from the water-supply rollers. Further, supply of water to the water-supply rollers is conducted from a water-supply container in Unexamined Japanese Patent Publication No. 11-161107, wherein, water is coated on a circumference surface of the porous roller from the water-supply roller, when the water-supply roller dipped in the water-supply container is rotated.
In a process of humidifying sheets, foreign matters such as paper dusts sticking to the sheet spread from the sheet to a humidifying roller, then, from the humidifying roller to a water-supply roller, and further, from the water-supply roller to the water-supply container to be mixed to spread in a sheet humidifying device.
Then, foreign matters mixed in the aforesaid water-supply container stick again to the water-supply roller and the humidifying roller, thus, uniform humidification of water on entire surface of the sheet is interrupted by the foreign matters on the porous roller and on the water-supply roller, which is a problem.